SHINKAY, Afghanistan – A battered taxi sped up a dusty road toward a squad of Afghan soldiers searching for bombs planted in the dirt. Army gunmen who had fanned out for protection readied for a suicide attacker. The car screeched to a halt. The soldiers recognized a local Taliban fighter in the passenger seat and pointed their guns at him when they saw he was armed. "Relax guys," said Rahimullah, the Taliban fighter. He nervously stepped out of the taxi, holding his Kalashnikov rifle by the barrel to show he didn't intend to shoot. "Can't you see it's a new Kalashnikov?" said Rahimullah, who like many Afghans goes by one name. "It's from the government: I've changed sides." The soldiers grabbed the weapon for a closer look. It was, indeed, newly issued. Rahimullah said he'd received it for leaving the insurgency to become a police officer. But the scruffy 22-year-old still wore an insurgent's typical uniform: a white gown, ragged camouflage jacket and black bandanna that soldiers recognized from when they battled his faction in the Tagab valley a few weeks earlier. He had no identification on him or proof he had changed sides. The tense encounter, fraught with risks for both the soldiers and Rahimullah, illustrates the challenges facing NATO and Afghan authorities as they try to turn former enemies into trusted government agents. Officials say a key measure is peeling off small-time local fighters from extremist militants. But securing these shifting loyalties is tricky. Hundreds of police and some soldiers are known to have switched back once they were trained and armed. In October, a policeman opened fire on the British troops training him, killing five. Last year, police officers turned against American soldiers in two separate incidents, killing and wounding several. The soldiers were stunned to see Rahimullah casually come up the road in broad daylight, claiming to be with the government. Rahimullah claimed he was heading to Kabul, the capital some 50 miles to the west, where officials had promised him a police uniform and card. "We've got to be very careful with these people, we never know," said Capt. Abdul Hashem, the Afghan army officer commanding the mine clearance team that stopped Rahimullah last week. Hashem made a round of calls on his cell phone to check the turncoat's story. Hashem reluctantly gave Rahimullah back his gun when senior officers confirmed the farmer belonged to a Taliban faction whose commander was now slated to become the local police chief. The commander, Sayyed Ahmed, had fallen out with other Taliban chiefs in Tagab valley, where NATO officers estimate some 300 militants operate. His group of about 30 men was cornered by Afghan soldiers, who said they killed about a dozen during a clash in September. Ahmed called it quits and offered his services, they said. "We have proof of his loyalty," said Capt. Romaric, a French mentoring officer living with a handful of men at an Afghan combat outpost on Tagab valley's front line next to Shinkay village, where Rahimullah lived. Romaric, who gave only his first name because of French army field rules, said he and Afghan officers had confirmed that senior Taliban leaders were now after Ahmed and his men. "They've called from Pakistan to say they assigned a suicide bomber to finish him," he said. Rahimullah didn't mind the threat. Switching sides left him indifferent. "If my commander thinks it's the good choice, I'm sure he's right," he said, though he was taking a pay cut. His new salary as a police officer would be 6,000 Afghanis per month, or about $120. The Taliban paid him $300 a month, he said. "But the money was irregular." Though now viewed as renegade, Rahimullah said he'd rather stay in his valley, despite the threats from other insurgent groups still stationed nearby. "They have lunch with us, but they're still having dinner with the Taliban," he said. "We have a few weeks to show that we're the strongest."